This invention relates to the field of devices for filtering and treating aqueous solutions in a wide range of applications. In particular, the present invention relates to filtration cartridges, which employ combination of porous materials for mechanical filtration and granulated activated carbon as a chemical absorbent. Such filtration cartridges are typically used in the field of aquarium filters and filtering equipment. In aquarium settings the water from the aquarium is drawn through a filtration cartridge placed into a container by means of a water pump and then returned to the aquarium.
A filter cartridge is shown in U.S. Pat. No. 4,483,769 to Sherman, U.S. Pat. No. 5,053,125 to Willinger, et al., and U.S. Pat. No. 5,728,293 to Guoli, et al.
The Sherman device uses a back stiffener structure with plurality of slots for water passage and channels filled with granulated activated carbon. A porous filter material is secured to the front of the structure to cover the channels. The water flows through the porous material to the carbon, through the carbon, and then through the back structure slots returns to the aquarium. At some point of time this type of filtration cartridge becomes clogged and must therefore be removed and replaced. The newly replaced filtration cartridge is free of microorganisms while the old filtration cartridge with microorganisms is discarded. This creates a void in filtering ability until the microorganisms re-establish themselves in the replaced filtration cartridge. Additionally, since the filtration cartridges of this type are entirely sealed, the amount of carbon or other type of chemical reagent in the cartridge cannot be individually adjusted.
The Willinger, et al. filter uses a framework within a disposable filter bag that is filled with carbon. In vertical installations this type of filtration cartridge usually accumulates the carbon in the lower portion of the cartridge. Upon clogging the water flows through the top portion of the cartridge, thus bypassing the carbon, which in turn results in lack of chemical filtration. The framework limited surface area does not support colony of microorganisms sufficient to provide for the uninterrupted level of biological filtration once the old filter bag is being replaced with a new one.
The Guoli, et al. filter uses a separate planar framework with plural groups of vanes projecting from one side of the plate for promoting biological filtration. A separate disposable unit with its own framework similar to the one of Sherman's device must be used in addition with the plate. Thus the filtration employs two separate cartridges to achieve mechanical, chemical and uninterrupted biological filtrations. In addition since the disposable units of this type are entirely sealed, the amount of carbon or other type of chemical reagent in the cartridge cannot be individually adjusted.